Better fuel economy and enhanced safety are benefits from lower hood lines on trucks and other motor vehicles. A lower hood line improves a truck's aerodynamics, thus reducing fuel consumption. A lower hood line also improves the line of site of the driver, thus providing for safer operation of the truck or motor vehicle.
One obstacle to lowering the hood line is the position of the cooling fan on the engine. The cooling fan is mounted above the crankshaft in many configurations. The crankshaft powers the fan to cool the engine through pulleys and a fan belt.
In contrast, a crankshaft-mounted cooling fan enables the hood line of a truck or motor vehicle to be lowered. It eliminates the need for pulleys and a fan belt to drive the fan. Consequently, there is more space in the engine cavity for auxiliary equipment. Alternatively, the engine cavity may be reduced. In addition, an engine is more reliable without a fan belt.
Even with these benefits, typical crankshaft-mounted cooling fans have adverse effects on engine performance and operation. These fans run only at the speed of the crankshaft, i.e. the engine speed. Consequently, the fan does not run fast enough when the engine needs the most cooling during idle, slow speeds, and other times.
Moreover, these fans cannot be disengaged from the crankshaft when the engine does not need the fan. For example, an engine does not need the fan to operate during engine warm-up. An operating fan would extend the warm-up period and take energy from the engine. Similarly, an engine does not need the fan to operate when the truck or motor vehicle is moving at higher speeds. The airflow at higher speeds is sufficient to cool the engine. In addition, an operating fan becomes a drag on the engine, reducing engine performance and lowering fuel efficiency.
Finally, a typical crankshaft-mounted fan prohibits power takeoff from the front of the engine. With the fan blocking the crankshaft, it is impossible to connect a power takeoff device to the crankshaft. Consequently, these fans limit the use of power takeoff devices to the rear of the truck or vehicle.
Accordingly, there is a need for a crankshaft-mounted cooling fan that operates faster than the engine speed, can be turned on/off when needed, and has power takeoff capability through the crankshaft.